AT526465A1 - Method and device for embossing structures - Google Patents

Abstract

The invention relates to a method for embossing at least one micro- or nanostructure with an embossing stamp (1) having at least one embossing structure (2), with the following steps, in particular the following sequence: - Alignment of the embossing structure (2) of the embossing stamp (1) relative to a metering device ( 4), - metering an embossing compound (6) into the embossing structure (2) by means of the metering device (4), - at least partially curing the embossing compound (6) and embossing the embossing compound (6), characterized in that the embossing structures (2) at least point in a gravitational direction (G) when dosing. The invention further relates to a corresponding device.

Description

-1-

Method and device for embossing structures

Description

The invention relates to a method according to claim 1 and one

Device according to claim 5.

The production of structures in the micro and/or nanometer range is increasingly done using imprint lithography. Imprint lithography has been able to assert itself more and more over photolithography in recent years. The advantages of imprint lithography lie primarily in the possibility of producing structures in the nanometer range, which would not be possible to produce using photolithography or would only be possible with extreme effort. Today, nano- and/or micrometer-sized patterns can be produced on the surface of substrates with high precision and accuracy in a mass-produced process. Although the advantages of imprint lithography lie primarily in the production of structures in the nanometer range, there is also a very large area of application for imprint technologies in the micrometer range, especially in

the lens embossing technique.

The lens embossing techniques can be used in embossing techniques for producing so-called monolithic lens wafers. The manufacturing process is called monolithic lens molding.

abbreviated: MLM). With this technique, multiple lenses are used as part

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one and the same substrate. The lenses are not separated from each other and therefore do not necessarily rely on a carrier substrate, although a connection to a carrier substrate or any other, second substrate

can be produced.

In another embossing technique, the lenses are embossed at the same time, but are not connected to each other via the embossing compound. For quick and efficient further processing, this embossing is usually done on a carrier substrate. Drops of the embossing compound are deposited on the carrier substrate, usually by a dispensing system that moves relative to the rigid carrier substrate. There is then an approximate relative movement between the embossing stamp and the carrier substrate. Preferably, only the stamp is moved relative to the static carrier substrate. Each individual lens should be as symmetrical as possible. This is particularly guaranteed if the drops of embossing compound are positioned exactly under the embossing structures. Furthermore, it must be ensured during the embossing process that the embossing stamp (and thus the embossing structures) does not shift relative to the embossing material drops in an X and/or a Y direction during the approach in the Z direction. The drops of the embossing compound can be partially pushed to the side and shaped during the embossing process, but they generally no longer leave their position on the carrier substrate, since the predominant adhesion between the carrier substrate and

Embossing material is too large for this. A third embossing technique uses a so-called step

and-Repeat embossing stamp. The step-and-repeat embossing stamp is included

smaller

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as the substrate on which the lenses are to be embossed. In general, the step-and-repeat embossing stamp only has a single lens shape and can therefore only emboss a single lens per embossing step. In this embossing technique, drops of the embossing compound are preferably distributed on a substrate. The step-and-repeat embossing stamp then approaches each drop individually and carries out the embossing. In special cases, it is also conceivable to deposit a full-surface layer of embossing material, which is then structured using a step-and-repeat embossing stamp. Some step-and-repeat embossing stamps have several lens shapes of the same or different shapes and are therefore between the full-surface and pure step-and-repeat embossing stamps. You can

Accordingly, emboss several lenses at the same time per embossing step.

The quality of an embossed product, for example a lens wafer, or corresponding individual lenses on a carrier substrate, therefore depends very much on the interaction between the stamp and the embossing compound. During the dispensing of the embossing compound and/or the embossing process, defects such as gas bubbles, differences in thickness along the surface, density inhomogeneities,

gradient or asymmetrical embossing material etc. arise.

Due to the highly viscous embossing compound, gas bubbles are usually not generated during the embossing process, but are already in the embossing compound, for example due to incorrect filling of the dispensing system. However, such gas bubbles can sometimes

also arise during dispensing itself.

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The differences in thickness along a surface are usually a result of an existing wedge error and can be largely eliminated by correct positioning between the embossing die and the carrier substrate

be avoided.

Any density inhomogeneities are more of a chemical nature and less caused by the dispensing system. However, during a curing process, the crosslinking of a polymer can occur to different extents at different locations and one

result in corresponding density inhomogeneity.

Asymmetrical embossing compounds can occur especially when dispensing drops. The embossing compound is distributed in individual drops over a surface and is not completely symmetrical to the embossing structures that deform it, so that during and/or

After embossing, an asymmetrical single lens is created.

One of the biggest problems with today's embossing technology is the incomplete distribution or filling of the embossing structures of the embossing die by the embossing compound. During the embossing process, the stamp presses the embossing material radially outwards. At the same time, the embossed structures are filled with the embossing compound. This process allows ambient gases to be trapped between the embossing compound and the surface of the embossing structures of the embossing stamp. These ambient gases create corresponding bubbles and thus destroy the homogeneity of the material. This can have fatal consequences, especially with optical products such as lenses. Lenses with such effects would exhibit lens defects, particularly chromatic and spherical aberrations. It would be

conceivably, one

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to allow the corresponding embossing process to take place in a vacuum. For this purpose, the corresponding chamber must be evacuated before each embossing process. After successful embossing, the chamber would be ventilated again. These processes are correspondingly time-consuming and therefore

very expensive.

Another problem that occurs especially when dispensing drops of embossing material to produce individual lenses distributed on a carrier substrate is the symmetry of the individual lenses. A poorly positioned drop of embossing compound on the carrier substrate and/or poor approximation of the embossing die, and therefore of the embossing structures, with respect to the drops of embossing compound

asymmetrical lens shapes.

Another problem is the flow of the embossing compound, which particularly affects the adhesion properties between the embossing compound and

the corresponding surface.

The object of the present invention is therefore to solve one or more of the aforementioned technical problems with a method and/or a

To solve the device according to the following description.

This task is solved with the features of claims 1 and 5. Advantageous developments of the invention are specified in the subclaims. All combinations of at least two of the features specified in the description, the claims and/or the figures also fall within the scope of the invention. At

The specified value ranges should also be within the stated values

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Values lying within the limits are considered limit values and in

can be used in any combination.

The invention is based on the idea of solving the technical problems mentioned by dispensing an embossing compound into embossing structures against gravity, in particular by aligning the dispensing direction of a metering device against gravity, i.e. against a gravitational direction G and/or by aligning embossing structures, in particular an axis of symmetry the respective embossing structure, parallel to gravity and/or in the direction of gravity

G pointing.

The invention is therefore particularly concerned with a method and a system for avoiding gas inclusions between the surface of the embossing structure of the embossing stamp and the embossing compound, as well as a method for continuous and/or controlled curing

the embossing material.

Furthermore, the invention concerns a method and a system which ensure that the embossing material carries out self-assembly into a predetermined shape. This self-assembly is a direct result of several physical factors

Effects.

Another aspect of the invention is the prevention or

at least the suppression of the lateral flow of the embossing material. The invention has the advantages of self-assembly of the embossing material

in the corresponding embossed structure, a material saving through one

targeted and precisely calculated dispensing/dosing, one

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Symmetry and uniform distribution of the embossing compound in the embossing structures, a localized edge layer hardening of the embossing compound, which counteracts deformation of the edge layer

set embossing material, not hindered or prevented.

Furthermore, the dispensing method according to the invention prevents the embossing material from flowing in a lateral direction due to gravity. According to the invention, gravity ensures that a convex embossing compound surface is formed in the direction of the carrier substrate, which prevents the embossing compound from running laterally. Furthermore, the convex embossing compound surface enables point contact of the embossing compound with the substrate surface. By moving the embossing stamp further towards the carrier substrate, the contact area of the embossing compound surface with the carrier substrate increases continuously, starting from the contact point, and thus prevents

unwanted gas inclusions in the simplest way.

The invention describes in particular a method and a system for embossing micro- and/or nanometer-sized structures. One idea according to the invention is an efficient, simplified, inexpensive method for locally limited and defect-free distribution of an embossing compound. According to the invention, the embossing compound is dispensed into the embossing structures of the embossing stamp against gravity. The filling of the embossing structures of the embossing stamp is not only made possible but also supported by the adhesion forces between the surface of the embossing structure and the embossing compound. The adhesion, the curvature of the embossed structures and the pressure generated by a nozzle lead to tangential forces on the

Embossing compound, which leads to one

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Wetting of the embossed structure surface leads. During the wetting process, any gas that may exist in the environment is pushed ahead of the embossing material shaft. A possible formation of undesirable gas inclusions therefore does not occur. Furthermore, the embodiment and method according to the invention prevents the embossing material from flowing in the lateral direction due to gravity, i.e

along the embossed structure surface.

According to a further aspect of the invention, the invention describes in particular a system for dispensing an embossing compound into an embossing structure of an embossing stamp. During filling, the embossing structures of the embossing stamp are located above a substrate on which the embossing process is to be carried out. The system according to the invention therefore consists of at least a sample holder, an embossing stamp and a dispensing device,

which embossing material can dispense/dose against gravity.

The following sections discuss the two basic types of

Stamps for embossing lithography will be presented.

In imprint technology, a distinction is made between two types of embossing stamps, hard stamps and soft stamps. Each stamping process can theoretically be carried out with a hard stamp or a soft stamp. However, there are several technical and financial reasons to use the hard stamp itself only as a so-called master stamp and, whenever necessary, to mold a soft stamp from this master stamp, which is then used as the actual structural stamp. The hard stamp is therefore a negative of the soft stamp. The hard stamp is only for manufacturing

several

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Soft stamp required. Soft stamps can be distinguished from hard stamps by different chemical, physical and technical parameters. A distinction based on the elasticity behavior would be conceivable. Soft punches have a deformation behavior based primarily on entropy elasticity, hard punches primarily on energy elasticity. Furthermore, the two types of stamps can be distinguished, for example, by their hardness. Hardness is the resistance that a material offers to an incoming body. Since hard stamps are primarily made of metals or ceramics, they have correspondingly high hardness values. There are different ways to specify the hardness of a solid. A very common method is to specify the Vickers hardness. Hard stamps according to the invention preferably have a Vickers hardness of

more than 500 HV.

Hard stamps have the advantage that they can be manufactured directly from a component made of a material with high strength and high rigidity using suitable processes such as electron beam lithography or laser beam lithography. Such hard stamps have a very high hardness and are therefore more or less wear-resistant. However, the high strength and wear resistance are offset by the high costs that are necessary to produce a hard stamp. Even if the hard stamp can be used for hundreds of embossing steps, over time it will no longer show negligible wear. Furthermore, removing the hard stamp from the embossing compound is technically difficult. Hard punches have a relatively high bending resistance. They are not particularly easy to deform, so ideally they have to be in the normal direction

be withdrawn. When demolding the hard stamps after

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During the embossing process, the embossed nano- and/or microstructures can regularly be destroyed, since the hard stamp has a very high rigidity and can therefore destroy the micro- and/or nanostructures of the embossing material that has just been molded. Furthermore, substrates can have defects that can subsequently lead to damage or destruction of the hard stamp. However, if the hard stamp is only used as a master stamp, the molding process of the soft stamp from the master stamp is very easy to control and with very little wear on the master stamp

tied together.

Soft stamps can be produced very easily using replication processes from the master stamp (hard stamp). The master stamp represents the negative corresponding to the soft stamp. The soft stamps are embossed on the master stamp, then removed from the mold and then used as a structural stamp for embossing the stamp structures onto a substrate. Soft stamps are much easier, gentler and less problematic to remove from the embossing material than hard stamps. Furthermore, any number of soft stamps can be molded from one master stamp. After a soft stamp shows a certain amount of wear, the soft stamp is discarded

and forms a new soft stamp from the master stamp.

Embodiments according to the invention are preferred

Hard stamp used. The sample holder is preferably a vacuum sample holder. Would be conceivable

also the use of an electrostatic sample holder, one

Sample holder with magnetic or electrical fixation

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Sample holder with a changeable adhesion property or with

an appropriate mechanical clamping.

The embossing stamp has on its embossing side, in particular several, preferably distributed, in particular regularly arranged, embossing structures over the entire embossing surface of the embossing side. These can, for example, be concave lens shapes that serve as negatives for the correspondingly embossed convex lenses. The diameter of the lenses is particularly large compared to the depth of the lens. The ratio of diameter to depth of the lens shapes is in particular greater than 1, preferably greater than 10, more preferably greater than 20, most preferably greater than 50, most preferably greater than 100. A correspondingly large ratio guarantees the unhindered according to the invention, continuous, lateral flow and freedom from bubbles of the embossing material. Alternatively, a structure is conceivable, in particular a lens shape, in which the diameter is smaller than the depth. The ratio of depth to diameter of the lens shapes is then in particular greater than 1, preferably greater than 10, more preferably greater than 20, with the greatest

Preference greater than 50, with the greatest preference greater than 100.

According to the invention, the embossing material is hardened in particular by chemical and/or physical processes. In particular, the embossing material is either by electromagnetic radiation and/or by

Temperature cured. Hardening is preferably carried out using electromagnetic radiation,

with particular preference for UV radiation. In this case the

Embossing stamp preferred transparent for the necessary

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electromagnetic radiation if the embossing compound is to be hardened from the embossing stamp side. This is according to the invention

This is particularly the case when the embossing material hardens gradually.

A corresponding radiation source is preferably arranged behind the embossing stamp (i.e. on the side facing away from the embossing structures). The embossing stamp is therefore particularly transparent in a wavelength range between 5000nm and 10nm, preferably between 1000nm and 100nm, more preferably between 700nm and 200nm, most preferably between 500nm and 300nm. The optical transparency of the embossing stamp is greater than 0%, preferably greater than 20%, more preferably greater than 50%, with the greatest

Preference greater than 80%, with the greatest preference greater than 95%.

If the embossing compound is thermally hardened via the embossing stamp, the embossing stamp has, above all, a very high thermal conductivity in order to transport the heat on the back of the stamp to the embossing compound as quickly as possible. The thermal conductivity of the embossing stamp is in particular greater than 0.1 W/(m*K), preferably greater than 1 W/(m*K), preferably greater than 10 W/(m*K), most preferably greater than 100 W/(m*K), most preferably greater than 1000 W/(m*K).

Furthermore, the embossing die should have a correspondingly low heat capacity for the lowest possible thermal inertia. The specific heat capacities should be less than 10 kJ/(kg*K), preferably less than 1 kJ/(kg*K), more preferably less than 0.1 kJ/(kg*K), most preferably less than 0.01 kJ /(kg*K), most preferably smaller than 0.001 kJ/(kg*K).

This allows

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Temperature changes in the heat source as quickly as possible

Embossing material can be passed on.

The curing temperature of the embossing material is in particular greater than 25°C, preferably greater than 100°C, most preferably greater than 250°C, most preferably greater than 500°C. For special applications, the invention can achieve curing temperatures of more than 700 ° C, preferably more than 800 ° C, more preferably more than 900 ° C, most preferably around 1000 ° C, especially when used with embossing materials in which a Sintering process

is carried out.

According to the invention, it is also conceivable for the embossing materials to harden via a radiation source in or on the sample holder. All features mentioned for the embossing stamp apply analogously to the sample holder, in particular as an alternative or additional radiation source. An additional source in the sample holder can, above all, accelerate and promote complete hardening of the embossing compounds at the end of each process according to the invention. Above all, simultaneous, two-sided curing results in particular efficiency and homogeneity, but especially flexibility

when controlling the curing process.

A further advantage according to the invention of dosing/dispensing the embossing material against gravity (gravity acting on the embossing material during dosing/dispensing) is that gravity in each of the two methods according to the invention mentioned

ensures that the embossing material does not run in a lateral direction.

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A further aspect according to the invention for dispensing the embossing compound against gravity is an adhesion force between the embossing compound and the embossing structure surface, which, in particular through the choice of material and/or surface treatment, is set to be greater than the weight or the weight of the embossing compound. The ratio between the weight and the adhesion force is less than 1, preferably less than 0.1, more preferably less than 0.01, most preferably less than 0.001, most preferably less than

0.0001.

Particular attention is paid to ensuring that the adhesion is as low as possible so that the embossing die can be removed from the mold as easily as possible in the last process step, the demolding step. The adhesion energy surface density, in short the adhesion force, is in particular less than 1 J/m2, with greater preference less than 0.1 J/m2, with greater preference less than 0.01J/m2, with greatest preference

less than 0.001J/m2, most preferably less than 0.0001J/m2.

The viscosity of the embossing compound is preferably very low so that the embossing compound can be distributed easily and quickly in the lens mold. The viscosity is in particular less than 100,000 mPas, preferably less than 1000 mPas, more preferably

less than 5 mPas, preferably less than 1 mPas.

The dispensed volumes of the embossing material are in particular larger than 0.0001 µl, preferably larger than 0.001 µl, most preferably larger than 0.1 µl, most preferably larger than 10 µl, most preferably larger than 500 µl.

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According to the invention, it is particularly conceivable that the device according to the invention and the method according to the invention are used to produce a monolithic lens wafer by depositing enough embossing compound that the embossing compounds in the individual lens shapes combine laterally with one another on the substrate before embossing. In particular, by metering the embossing compound per lens mold in such a way that there is no contact between the embossing compounds, the embodiment according to the invention can be used for the simultaneous embossing of individual lenses on a substrate. If, according to the invention, an embossing stamp is used that is smaller than the substrate on which the lenses are to be embossed, the process according to the invention is repeated many times in order to provide the entire substrate with lenses. Accordingly, that would be

Embossing technique can be called step-and-repeat embossing technique.

The embodiment according to the invention can be based in particular on the above

Embossing techniques described can be used

The system according to the invention can preferably be installed in a process chamber that can be hermetically sealed from the environment. This makes it possible to evacuate the process chamber and/or ventilate the process chamber with any gas or gas mixture. The process chamber can be evacuated to pressures of less than 1 bar, preferably less than 10°* mbar, more preferably less than 10:5 mbar, most preferably less than 10:® mbar. The main advantage of using a vacuum is that the unwanted inclusion of gas can be completely suppressed or at least improved

(preferred version)

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and/or during and/or after the deposition of the embossing material each

Type of gas is removed from the process chamber.

According to the invention, the process chamber can in particular be flushed with any gas or gas mixture. This is particularly advantageous if the embossing is not to take place under a vacuum. A possible, but not the only, reason for not using a vacuum would be the high volatility of the embossing material at low ambient pressure. The slight volatility, which is characterized by a high vapor pressure, can significantly contribute to contamination of the process chamber. The gas used should then have as little interaction as possible with the embossing material. Flushing with an inert gas that does not interact with the embossing material would be particularly preferred. This would be particularly conceivable

use of

e Argon and/or

ee helium and/or

e carbon dioxide and/or

e carbon monoxide and/or e nitrogen and/or

* Ammonia and/or

e hydrogen.

If embossing materials are used that are to be influenced by a gas, correspondingly reactive gases are preferably used. In very special embodiments, it is conceivable that the process chamber is pressurized. The pressure

in the process chamber is greater than 1 bar, preferably greater than 2

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bar, with greater preference greater than 5 bar, with greatest preference greater than 10 bar, with greatest preference greater than 20 bar. The excess pressure is preferably generated with one of the gases mentioned above or a corresponding gas mixture. However, this is also conceivable

Use of oxygen or air as a gas mixture.

To the extent that device features are disclosed here and/or in the subsequent description of the figures, these should also be considered as

Procedural features disclosed apply and vice versa.

Further features and embodiments of the invention emerge from the claims and the following description of the figures

Drawing. The drawing shows in:

Figure 1 shows a schematic cross-sectional representation of an embodiment of a system according to the invention with a carrier substrate, embossing stamp and a dispensing device for dispensing/dosing

against gravity,

Figure 2a shows a schematic cross-sectional representation of a first step of a first embodiment of the

Method according to the invention with centric dosing, Figure 2b is a schematic cross-sectional representation of a second

Step of the first embodiment of the invention

procedure,

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Figure 2c shows a schematic cross-sectional representation of a third step of the first embodiment of the invention

procedure,

Figure 2d shows a schematic cross-sectional representation of a fourth step of the first embodiment of the invention

procedure,

Figure 2e is a schematic cross-sectional representation of a fifth step of the first embodiment of the invention

procedure,

Figure 2f shows a schematic cross-sectional representation of an end product of the first embodiment

method according to the invention,

Figure 3a shows a schematic cross-sectional representation of a first step of a second embodiment of the

non-centric dosing method according to the invention,

Figure 3b is a schematic cross-sectional representation of a second step of the second embodiment

Method according to the invention, Figure 3c is a schematic cross-sectional representation of a third

Step of the second embodiment of the

method according to the invention,

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Figure 3d shows a schematic cross-sectional representation of a fourth step of the second embodiment

method according to the invention,

Figure 3e is a schematic cross-sectional representation of a fifth step of the second embodiment

Method according to the invention and

Figure 3f shows a schematic cross-sectional representation of an end product of the first embodiment

Method according to the invention.

In the figures, parts that are the same or have the same effect are marked with uniform reference numbers, with the size ratios being the same

Illustration is not to scale.

Figure 1 shows a schematic representation of an embodiment of a device according to the invention, wherein a housing and handling devices such as robots or alignment devices for alignment or a control device for controlling the functions and features described according to the invention are not included

are shown.

The following three components can be moved and aligned relative to one another:

- an embossing stamp 1 with embossing structures 2, in particular provided on a back 1r with a radiation source 7, the embossing stamp 1 with its embossing structures 2 in one

is arranged and/or can be arranged facing the gravitational direction G,

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- a carrier substrate 3 that can be fixed on a sample holder 11 or chuck

- a metering device 4 with a nozzle 5, which can be arranged between the embossing stamp 1 and the carrier substrate 3, the metering device 4 dispensing an embossing compound 6 counter to

Gravity direction G can execute.

Figures 2a-2f show a first dispensing method with central dispensing/dosing of the embossing compound 6 using the example of one of the large number of embossing structures 2 of the embossing stamp 1 as well as embossing the dosed embossing compound 6 into a, in particular hardened, lens 9. Centric means that the dosage along an axis of symmetry

each embossed structure 6 takes place.

A decisive advantage of direct dispensing or dosing of the embossing compound 6 into the embossing structures 2 instead of dispensing a drop of embossing compound onto a carrier substrate 3 is the self-assembly of the embossing compound 6 in the embossing structure 2. This results in a symmetrical distribution of the embossing compound 6 caused by gravity achieved in relation to the embossing structure 2. This ensures that there is a symmetrical distribution of the embossing compound 6 before the embossing compound 6 comes into contact with the carrier substrate 3

(i.e. before minting). This self-assembly is a result of the effort to be one

To create force balance between the surface forces

exist between the phase interfaces.

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In a first process step according to FIG. 2a, the nozzle 5 is positioned centrally to the embossed structure 2 and aligned against the direction of gravity G. As a result, the embossing compound 6 is dispensed centrally into the respective embossing structure 2. The central dispensing also results in a symmetrical, in particular radially symmetrical, filling of the concave embossing structure 2. It should be noted that this dispensing process creates the possibility of the inclusion of gas bubbles 10. The amount of all gas bubbles 10 in several lenses 9 on the carrier substrate 3 can be very small. The gas bubbles 10 can also migrate until the embossing compound 6 has completely hardened. Due to the fact that the gas bubble 10 has a lower density than the embossing compound 6, the gas bubble 10 moves against gravity, i.e. towards an embossed structure surface 20 of the embossing structure 2, i.e. onto a surface

90 of the lens 9.

The diffusion speed of the gas bubble 10 in the embossing compound 6 against the gravitational direction G depends on the rheological conditions. The movement of the gas bubble 10 in the embossing compound 6 is highly dependent on the viscosity of the embossing compound 10. It can therefore happen that the gas bubble 10 does not reach the embossed structure surface 20 before the embossing compound 6 has completely hardened

has taken place.

After the embossing compound 6 has been metered into the respective embossing structure 2, the gravitational force acting on the embossing compound 6 creates a convex shape in a second process step according to FIG. 2b

Embossing compound surface 60. The embossed structures 2 become sequential

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filled until all embossed structures 2 have a certain amount

Embossing compound 6 is filled.

In a third process step according to Figure 2c, according to a further, in particular independent, aspect of the invention, the embossing compound 6 is hardened, in particular gradually, from the back side Ir of the embossing stamp 1. For this purpose, the embossing stamp 1 is transparent to electromagnetic radiation 8 from the radiation source 7. In a particularly preferred embodiment, the gradual curing is stopped after the embossing compound 6 has been hardened at least along the embossing structure surface 20. Due to the gradual hardening, each of the lenses 9 is hardened on a lens surface 90, while a lens base 9b further away from the radiation source 7 is still viscous and deformable, i.e. with that

Carrier substrate 3 can be deformed and embossed.

In a fourth process step according to the invention according to Figure 2d, the embossing takes place by a relative approach between the embossing stamp 1 and a carrier substrate 3. In this case, the embossing compound 6, which is still viscous towards the carrier substrate surface 30, becomes each

Lens 9 deformed at the same time.

In a fifth process step according to FIG. 2e, a complete process takes place

Hardening of the embossing compound 6 and thus the completion of the lenses 9. In a final process step, the simultaneous

Removal of the embossing die 1 from the hardened embossing compound 6,

so the lenses 9.

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According to a special, in particular independent, embodiment of the dispensing method according to the invention, the dispensing of the embossing compound 6 according to Figures 3a-3b takes place asymmetrically to the embossing structure 2. The embodiment according to the invention reduces or prevents the inclusion of gas bubbles. The embossing material 6 is dispensed in a dispensing direction D, in particular parallel and opposite to the direction of gravity G, which is offset from the axis of symmetry S by a distance dx. The ratio between the distance dx and half of the lens diameter, the lens radius, is greater than or equal to 0, preferably greater than 0.1, preferably greater than 0.4, more preferably greater than 0.6, with the greatest preference between 0.8 and 1.0. Some commonly used absolute values for the distance dx are also disclosed. The distance dx is greater than 0, preferably greater than 10um, with greater preference greater than 100um, with the greatest preference greater than 1000um, with the greatest preference greater than 5mm. The embodiment is in particular independent of the

Gravity direction G.

The radius of curvature R of the embossed structure surface 20 creates a tangential force Ft, which pulls the embossing compound 6 into the embossed structure 2 and thereby fills it symmetrically. The tangential force Ft is preferably a result of the pressure force with which the embossing compound 6 emerges from the nozzle 5 and/or the capillary force which arises from the curvature R of the embossing structure 2. The capillary force is primarily a result of the pressure difference of the gas inside the embossed structure 2 and outside the embossed structure 2. The pressure difference arises primarily from the different evaporation pressure

Embossing compound 6 on a curved section of the

24/34

“24 -

Embossing structure surface 20 with radius of curvature R and on a flat section 2e of the embossing die 1. According to the Kelvin equation, the saturation vapor pressure at the concavely curved section is smaller than at the flat section. Accordingly, there is a slightly lower vapor pressure inside the embossed structure 2 than at it

flat external surface.

The further process steps in Figures 3b-3f are carried out analogously to the process steps in Figures 2b-2f, but without the formation of gas bubbles 10. The prevention of the formation of gas bubbles 10 is primarily a result of the non-centric dispensing according to Figure 3a. As a result, the embossing compound front 6f advances continuously from one side of the embossing structure 2 along the curved section of the embossing structure surface 20 to the corresponding opposite side. Through this dispensing method of the embossing compound 6, only a very small area dD around the dispensing axis D is wetted with the embossing compound 6 and allows the embossing compound front 6f to assume the correct position continuously and through self-assembly. The small value range dD is shown in the drawings as the characteristic length of a surface section. For a circular surface, dD represents the diameter, for a square surface it represents the side, for a rectangular surface it represents the mean value of two mutually perpendicular sides. The characteristic length is greater than 0um, with greater preference greater than 10um, with greater preference greater than 100um, with greatest preference greater than 1000um, with the greatest

Preferably larger than 5mm.

The exact alignment of the dosing device 4 on an edge of the

Embossed structures 6, i.e. at the transition between the curved ones

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Sections of the embossing structures 6 and the flat section 2e of the embossing die 1, is much simpler and more precise than the centric one

Alignment.

The self-assembly process according to the invention with regard to the symmetrization caused by the dosing taking place counter to the gravitational direction G works in both embodiments

of the method according to the invention.

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Method and device for embossing structures

REFERENCE SYMBOL LIST

1 embossing stamp

lr back

2 embossed structure

20 embossed structure surface

2e Level section

3 carrier substrate

30 carrier substrate surface 4 dosing device

5 nozzle

6 embossing compound

6f embossing compound front

7 radiation source

8 Electromagnetic radiation 9 Lens

90 lens surface

9b lens base

10 gas bubbles

11 sample holders

D dispensing direction dx distance

S axis of symmetry

R radius of curvature Ft tangential force

G direction of gravity

Claims (4)

“27 - Method and device for embossing structures patent claims 1. Method for embossing at least one micro- or nanostructure with an embossing stamp (1) having at least one embossing structure (2) with the following steps, in particular the following Process: - Alignment of the embossing structure (2) of the embossing stamp (1) with respect to a metering device (4), - Dosing an embossing compound (6) into the embossing structure (2) by means of the dosing device (4), - at least partial hardening of the embossing compound (6) and embossing the embossing compound (6), characterized in that the embossed structures (2) at least point in a gravitational direction (G) when dosing. “28 - 2. The method according to claim 1, wherein the embossing material (6) before Embossing is partially and then completely hardened. 3. The method according to any one of claims 1 or 2, wherein the embossing compound (6) is eccentrically applied by means of a nozzle (5) of the metering device (4), in particular at an edge of the embossing structure (2). the embossed structure (2) is introduced. 4. Method according to at least one of the preceding claims, wherein the embossing compound (6) comes from a back side (1r). Embossed structure (2) is hardened. “29 - . Device for embossing at least one micro or Nanostructure with the following features: - a metering device (4) for metering an embossing compound (6) into the embossing structure (2), - Alignment means for aligning an embossing compound (6) into the embossing structure (2), - curing agent for curing the embossing compound (6), - Embossing means for embossing the embossing compound (6), characterized in that the embossing structures (2) at least pointing in a gravitational direction (G) during dosing can be aligned.